1. Field of the Invention
The present invention relates to an inflatable ball, in particular a soccer ball, having a shell comprising a plurality of panels.
2. Background Art
Soccer balls, as well as other inflatable balls, are typically produced as follows. In a first step an inner bladder, which can be made from latex, is reinforced with a carcass, or by a nylon thread wound around the bladder. An outer shell is then arranged on the carcass or on the nylon winding.
For simple balls the shell can be integrally formed of plastic material, or two preformed half shells of the ball shell are connected to each other, for example by gluing or sealing, as it is disclosed in FIG. 5 of the U.S. Pub. No. 2009/0011878. The present invention is related to higher quality balls. The shell of high quality balls is composed of a multitude of prefabricated panels. To clearly distinguish these two fundamentally different constructions of a ball shell (i.e., a shell formed from two half shells and a shell formed from a multitude of prefabricated panels), in the following the term panel is taken to mean a separately prefabricated portion which forms less than a half of the ball shell.
The panels must be suitably attached relative to each other, for example by sewing the edges of the panels together or also by gluing the panels to the surface of the carcass. A direct gluing or (laser) welding of the edges of the panels to each other is also conceivable. For the sake of simplicity, the region in which two adjacent panels contact each ether, is simply called a “seam” in the following description, regardless of whether the panels are actually sewn to each other in a standard manner or whether they are fixed relative to each other in any other way in order to provide the outer shell of the ball.
In the past, the shell of soccer balls typically consisted of 32 pentagonal and/or hexagonal panels. However, more recent ball designs have a lower number of larger-sized panels. The new designs improve the ball control by the player, since each seam creates an inhomogenity, typically a localized stiffness, in the outer shell so that the ball reacts differently when kicked with a shoe in the centre of a panel than when being kicked in the seam area. Unavoidable production tolerances during the manufacture of the seam result in an oven greater inhomogeneity and are another reason why the player cannot perfectly control the ball and that a shot ball does not follow a precise flight path. Furthermore, the arrangement of many seams leads to deviations from perfect sphericity.
Using larger panels reduces these problems, since less seams are needed for the manufacture of the overall shell of a ball having the same size. In addition, the manufacturing costs are reduced for larger panels, since less effort is needed to interconnect the panels and/or to arrange them on the carcass. Also the production tolerances are lower since there are less possibilities to create faulty seams during production. This applies for the frequency of occurrence as well as for the extent of such production tolerances.
However, balls having large panels can have negative flight properties and can, for example, tend to have instability. As a result of aerodynamic effects, there can be unintended and unpredictable flutter movements of the ball. It is immediately apparent that these aerodynamic effects substantially impair a controlled play and precise shots. Similar problems also occur for inflatable balls for others sports, such as handball and volleyball.
For improving the aerodynamic properties, it is known from the U.S. Pat. No. 4,318,544 to provide a soccer ball with seven parallel grooves extending in a uniform pentagonal arrangement over the complete shell of the ball. The arrangement is such that there are no grooves on certain panels of the shell of the ball, whereas up to three groups of seven parallel grooves contact each other on other panels.
While this arrangement may improve the flight properties of the ball, it does not improve precision during play. The extremely different surface design of the panels leads to a very different behavior of the ball when contacting a shoe of a player. Both, during dribbling, but also for an aimed shot, the ball will behave differently depending on whether the shoe of the player hits a panel provided with the seven parallel grooves or a standard panel without any ridges.
Embodiments of the present invention are, therefore, based on the problem to provide a ball, in particular a soccer ball, having good properties both, when contacting the shoe of the player but also in the air, and therefore allows more precise play.